The GNU chess program searches a tree of possible moves using the negascout algorithm to a depth depending on available time, evaluating leaf positions with weights optimized by a genetic algorithm. The chess program is recompiled for each evaluation to avoid time lost loading weights and allow deeper search of the game tree, improving performance.

1. Evaluation within GNU-chess.
The GNU-chess program understands the current position in a game as
the root of a tree describing possible (legal) next moves
from the previous (higher) level. This tree is searched
with the negascout algorithm with pruning
to a certain depth which depends upon the available
time for a move. The positions at the bottom of the
search tree (leaves) are thereby first evaluated using the
weights which are manipulated and possibly optimized
by the genetic algorithm implemented in this work. We
point out that in accordance with our preparatory experiments
described in section 1.1, footnote 4, time
used for reading the evaluation weights from a file into
a chess program is time lost for searching the game
tree at larger depth and yields a disadvantage in performance.
Thus, we have chosen to recompile the chess
program which represents a phenotype for every fitness
evaluation.